Waveguide Combiner Pass-Through In-Coupler Grating
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Solution Overview
Problem
Waveguide combiners used in augmented reality systems face challenges such as luminance non-uniformity, color non-uniformity, and double-images due to the propagation of red, green, and blue channels across multiple waveguide layers, which affect the quality of overlaid virtual images on ambient environments.
Innovation Solution
The implementation of a pass-through in-coupler grating in a stack of waveguide layers, where each layer includes both in-coupler and out-coupler gratings, allows specific color channels to be in-coupled and out-coupled from distinct layers, reducing non-uniformities by controlling the propagation of light modes and enhancing the viewing angle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple color channels propagate through multiple waveguide layers, then the device can display full-color overlaid images, but luminance non-uniformity and color non-uniformity occur
Solution Approach 1:
The waveguide combiner is divided into multiple waveguide layers, with each layer dedicated to specific color channels. The first waveguide layer handles green and blue channels, while the second waveguide layer handles the red channel. This segmentation prevents cross-channel interference and ensures uniform luminance and color output for each channel.
2Adaptability or versatility
If multiple color channels propagate through multiple waveguide layers, then full-color imaging is achieved, but double-images are generated
Solution Approach 1:
Each color channel is assigned to a specific waveguide layer with dedicated in-coupler and out-coupler gratings. The first waveguide layer contains gratings for green and blue channels, while the second waveguide layer contains gratings for the red channel. This segmentation ensures that each color channel follows its own optical path, eliminating double-image artifacts.
3Adaptability or versatility
If a pass-through in-coupler grating is used to allow red channel to pass through the first waveguide layer, then the red channel can be in-coupled by the second waveguide layer, but the device complexity increases
Solution Approach 1:
The first waveguide layer acts as an intermediary for the red channel by incorporating a pass-through in-coupler grating that allows red wavelengths to transmit through without being coupled into the first layer. This enables the red channel to reach the second waveguide layer's in-coupler grating, which then properly couples it into the second layer. This intermediary approach simplifies the overall structure compared to having separate entry points for each color channel.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration reduces luminance and color non-uniformities, minimizes double-images, and improves the overall quality of overlaid virtual images by ensuring each color channel propagates and is viewed from the intended waveguide layer, thereby enhancing the augmented reality experience.
Implementation Method 1
Light is coupled into and out of augmented waveguide combiners using surface relief gratings
Implementation Method 2
Generated light is in-coupled into a waveguide combiner, propagated through the augmented waveguide combiner
Implementation Method 3
Light is coupled into and out of augmented waveguide combiners using surface relief gratings
Data Source
AI summary
Waveguide combiners having a pass-through in-coupler grating are described herein. The waveguide combiners include at least one microdisplay and a stack of at least two waveguide layers. In one configuration of a waveguide combiner described herein, the green FOV and the blue FOV only propagate in a first waveguide and the red FOV only propagates in a second waveguide. In another configuration of a waveguide combiner described herein, the blue FOV, the red FOV, and the green FOV only propagate in the first waveguide, the second waveguide, and a third waveguide respectively. The waveguide combiners including the stack of waveguide layers reduces luminance non-uniformity, color non-uniformity, double-images, and other non-uniformities of the overlayed images from a first microdisplay and, in some embodiments, a second microdisplay.